Determination of agricultural soil compaction affected by tractor passing using 3D finite element

Abstract

Recently, soil compaction is one of the main problems of farmers and the main parameters of efficiency reduction of crops in some areas due to increasing in weight and size of agricultural tractors and passing of them in the field.  In this research, for determining of soil compaction after tractor passing, the numerical and empirical methods were used.  In empirical method, a Massy Ferguson tractor with a 3 moldboard mounted plough was used.  The experiment was carried out in the university of Urmia farmland.  The soil’s physical properties were measured in three portions, front of wheels before transmission, after transmission frontal wheel and after transmission hinder wheel in depth of 0 - 5, 5 -10 and 10-15 cm respectively.  The resistance of soil was determined using penetrometer and determination of cone index (CI).  In numerical method, the finite element was utilized for simulation of soil and penetrometer interaction.  Since the penetration of penetrometer rod is as a function of time, the dynamic analyze and ABAQUS software was used for simulation.  In this research, the soil was supposed as Elastic-perfectly plastic material and linear elasticity and Drucker-Prager plasticity model was applied for indicating the elastic and plastic behavior of soil, respectively.  Finally, the necessary force for penetration in the soil was determined and compared with field experiments.  Results of finite element analysis in initial depth were near the field experiments results.  But in lower depth, results of the compacted soil layers demonstrated that the field results were higher than finite element results.

Keywords: soil, finite element, cone index, interaction